Additional information: Halo 4 does not use any engine technology from last year's Halo: Combat Evolved Anniversary.

"It shares no engine tech with Anniversary," O'Connor said. "Almost every single system, audio, rendering, lighting, you name it, has been either radically overhauled or rewritten from the ground up.

"At this point saying it's based on a previous version of the engine basically speaks to a few pieces of code."

And finally, O'Connor addressed concern over the apparent inclusion of perks in Halo 4 - a first for the series.

"There aren't 'perks' in the game as being described here," he said. "And classic Halo is still there. But there are things we will be rolling out soon to put all of this discussion in a much better perspective and I suspect calm frayed nerves."

Then: "We didn't mention them. That's why I put it in quotes. That term was coined by someone else to interpret stuff they saw in the UI. Not a big deal in the grand scheme of things and to be expected during announce fervour. And yes, it's partly our fault since we're rolling out more information about this stuff at a later time."

For the record, this is what Halo 4 creative director Josh Holmes said at last week's Microsoft showcase event in San Francisco, attended by Eurogamer.

"You, as a player, have the ability to customise all aspects of your Spartan warrior - and not just cosmetically. For the first time in a Halo title, you can actually change gameplay-impacting components. This allows you to customise load outs and gives you gameplay enhancements that can be unlocked through the progression system."